Lec 34 RNA Structure

- The flow of genetic information is generally form DNA to RNA to proteins
- DNA replication, transcription to RNA, translation to proteins

Relax flashcard, meditate lol

do not utilize the same central dogma as other organisms because DNA is not involved

• Single-stranded RNA can form complex structure with itself
• Stem loops have a double stranded portion and an unbase-paired portion
• Stems and loops can form randomly throughout RNA
• Base pairs can form between 3 bases which form a specific site

- RNA cleavage -> cleaves a phosphodiester bond
- Transesterification -> moving one ester group to
another

- a euk and pro endonuclease that cleaves the 5’-ends of precursor tRNAs

consist of a conserved catalytic core that targets specific mRNA, attaches itself, and cleaves and forms loops

- When the world did not have a lot of oxygen, RNA would self replicate as well as making proteins
- Membranes started to form compartments
- RNA at this time coded for both DNA and proteins -> but formation of DNA proved to be much more stable,
which is why the central dogma came into existence

translation, regulatory (5%)

translation, catalytic (80%)

translation (15%)

• DNA Template: The polymerase must use a DNA template to synthesize the new RNA fragment
- The DNA and RNA strand are the same except that T is replaced with U in RNA
• Activated precursor: Ribonucleoside triphosphate
• Divalent metal ions: Mg2+ or Mn2+
**no primer needed for RNA polymerase

opposite of mRNA (if that makes sense)
- U is replaced with T

opposite of template

DNA sequences that direct RNA polymerase to initiate replication

- Any RNA transcript made after the promoter is the + region
- Promoters are before the initiation site
• Prokaryotes: TTGACA & Pribnow box
• Eukaryotes: CAAT & TATA box

A sequence of DNA, RNA, or protein that represent aligned and related sequences (not the same as promoters)

Sequence that stops transcription
• Palindromic DNA
• Hairpin structure

RNA:
■ ATP, GTP, CTP, UTP required substrates
■ No primer
■ No proofreading by 3’ to 5’ exonuclease
DNA:
DNA
■ dATP, dGTP, dCTP, and dTTP required substrates
■ RNA or DNA primer required
■ Proofreading

- in eukaryotes, after transcription, the 5’ end of mRNA is modified by the attachment of a cap structure and the 3’ end acquires a poly(A) tail
- transcription processes pre-mRNA to mature mRNA

noncoding regions
■ Introns from certain organisms can self-splice, meaning they can excise
themselves
■ The average gene has 8 introns, while some have more than 100
■ Intron size ranges from 50-10,000 nucleotides
■ Initially detected by electron microscopy studies

coding regions
■ Encode discrete protein domains, are structural and functional units of
proteins
■ Some new proteins evolved by exon shuffling and/or exon duplication

a pre-mRNA can be spliced in different patterns, generating proteins with different functions